| 3551. |
- Skarin, A, et al.
(författare)
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Light and electron microscopic studies of anaerobic curved bacteria isolated from the vagina
- 1984
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Ingår i: Scandinavian Journal of Urology. - 0300-8886. ; 86, s. 59-64
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Tidskriftsartikel (refereegranskat)abstract
- Twenty strains of anaerobic curved rods isolated from vaginal secretion were studied with light and transmission electron microscopy. Ten of the strains were of a short (approx. 1.5 microns) Gram-variable type, while ten were of a long (approx. 3 microns) Gram-negative type. The former had one to four flagella and the latter between one and eight. The flagella originated from the concave aspect of the cells. Thin sections of both types of bacteria revealed an approximately 30 nm thick cell wall with no outer membrane, similar to that of most Gram-positive bacteria. An electron-dense zone in the middle of the cell wall, atypical of Gram-positive bacteria, was found, however. Amorphous and electron-translucent cytoplasmic inclusions, not membrane-enclosed, were detected. These inclusions stained metachromatically with Albert's stain.
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| 3552. |
- Skarin, A, et al.
(författare)
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Vaginal lactobacilli inhibiting growth of Gardnerella vaginalis, Mobiluncus and other bacterial species cultured from vaginal content of women with bacterial vaginosis
- 1986
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Ingår i: Acta pathologica, microbiologica, et immunologica Scandinavica. Section B, Microbiology. - : Wiley. - 0108-0180. ; 94B:6, s. 399-403
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Tidskriftsartikel (refereegranskat)abstract
- On a solid agar medium the growth-inhibitory effect of 9 Lactobacillus strains cultured from vaginal content was tested on bacteria cultured from vaginal content of women with bacterial vaginosis: Mobiluncus, Gardnerella vaginalis, Bacteroides and anaerobic cocci. Inhibition zones were observed in the growth of all of the strains isolated from women with bacterial vaginosis around all lactobacilli. The inhibitory effect of the lactobacilli was further tested on various anaerobic and facultatively anaerobic species, both type strains and fresh extragenitally cultured strains. Four Bacteroides fragilis strains as well as 2 out of 4 Staphylococcus aureus strains were clearly inhibited by the lactobacilli. The inhibition zones were generally wider at pH 5.5 than at 6.0. For all inhibited strains, (the S. aureus excepted) a low pH on the agar around the lactobacilli correlated to wider growth-inhibition zones.
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| 3553. |
- Skarping, Gunnar, et al.
(författare)
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Determination of cotinine in urine using glass capillary gas chromatography and selective detection, with special reference to the biological monitoring of passive smoking
- 1988
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Ingår i: Journal of Chromatography A. - 0021-9673. ; 454, s. 293-301
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Tidskriftsartikel (refereegranskat)abstract
- A capillary gas chromatographic (GC) method using selected-ion monitoring (SIM) was developed for the analysis of cotinine (C.A.S. No. 486-56-6) in human urine. The method is based on basic extraction of cotinine from 2 ml of urine into dichloromethane. After evaporation of the dichloromethane solution to dryness, 100 microliters of toluene were added, prior to GC-mass spectrometric (MS) analysis. Trideuterated cotinine (C.A.S. No. 97664-65-8) was used as the internal standard. More than 1000 automatic chromatographic analyses were made without column degradation. Molecular ions (M) of cotinine and trideuterated cotinine, (m/e = 176 and 179), were monitored in the electron impact (EI) mode and m/e = 177 (M + 1) and m/e = 180 (M + 1) in the chemical ionization (CI) mode with isobutane. The correlation coefficient with SIM and EI was 0.998 (5-20 ng/ml) and with CI was (0.2-2 ng/ml). For thermionic specific detection the correlation coefficient was 0.998 (10-510 ng/ml). Only capillary columns with an apolar bonded stationary phase film thickness of 1 micron showed sufficient inertness for cotinine analysis at the sub ng/ml level. The relative standard deviations for 5 and 20 ng/ml were 5.2 and 3.5% respectively (n = 12) using EI. Spiked urine samples from six non-smokers (5 ng/ml) showed a relative standard deviation of 5%. The overall recovery (25 ng/ml) was 100 +/- 4%. The minimum detectable concentration, using SIM, was ca. 2 ng/ml in the EI mode and ca. 0.2 ng/ml in the CI mode. The half-time for cotinine was ca. 18 h for both active smokers and non-smokers.
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| 3554. |
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| 3555. |
- Smeets, Ben, et al.
(författare)
-
A Comment on Niederreiter’s Public Key Cryptosystem
- 1986
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Ingår i: Advances in Cryptology — EUROCRYPT’ 85. EUROCRYPT 1985 : Proceedings of a Workshop on the Theory and Application of Cryptographic Techniques Linz, Austria, April 1985 - Proceedings of a Workshop on the Theory and Application of Cryptographic Techniques Linz, Austria, April 1985. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783540164685 - 9783540398059 ; 219, s. 40-42
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Konferensbidrag (refereegranskat)abstract
- In this comment we show that a recently proposed public key cryptosystem is not safe for most of the practical cases. Furthermore, it is shown that the security of this system is closely connected with the problem of computing logarithms over a finite field.
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| 3556. |
- Smeets, Ben
(författare)
-
GENERAL CLASS OF WINDMILL POLYNOMIALS FOR FAST M-SEQUENCE GENERATION.
- 1986
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Ingår i: ; , s. 115-115
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Konferensbidrag (refereegranskat)abstract
- Summary form only given. The windmill technique is an attractive alternative to the Lempel-Eastman technique for fast m-sequence generation. The author has generalized the class of linear recurrence relations for which the windmill technique results in an m-sequence generator. A converse to a set of known necessary conditions has been obtained.
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| 3557. |
- Smeets, B. J.M., et al.
(författare)
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Windmill generators a generalization and an observation of how many there are
- 1988
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Ingår i: Advances in Cryptology — EUROCRYPT 1988 - Workshop on the Theory and Application of Cryptographic Techniques, Proceedings. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783540502517 ; 330 LNCS, s. 325-330
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Konferensbidrag (refereegranskat)abstract
- The windmill technique has several practical advantageous over other techniques for high-speed generation or blockwise generation of pn-sequences. In this paper we generalize previous results by showing that if f(t)=α(t v) − β(t −v)t L is the minimal polynomial of a pn-sequence, then the sequence can be generated by a windmill generator. For L = 1,..127, and ν = 4, 8, 16 such that L ≡ ±3 mod 8 no irreducible polynomials f(t) were found. When L ≡ ±1 mod 8 the number of primitive f(t)’s was found to be approximately twice the expected number.
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| 3558. |
- Smeets, B. J.M., et al.
(författare)
-
Windmill pn-sequence generators
- 1989
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Ingår i: IEE Proceedings E: Computers and Digital Techniques. - : Institution of Engineering and Technology (IET). - 0143-7062. ; 136:5, s. 401-404
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Tidskriftsartikel (refereegranskat)abstract
- A windmill generator is a high-speed sequence generator capable of producing blocks of v consecutive symbols in parallel. It consists of v feedback-shift registers linked into a ring. The sequences are identical to those produced by a linear feedback-shift register with feedback polynomial of the special ('windmill') form f(t) = α(tv) - tLβ(t-v), where α(t) and β(t) are polynomials of degree less than L/v. L (relatively prime to v) is the degree of the polynomial, and is also the sum of the lengths of the registers making up the windmill. The connections of the windmill generator are specified by the coefficients of α(t) and β(t). The polynomial f(t) must be primitive if the output sequence is to be of maximal period. We have devised a search for windmill polynomials over the binary field that can generate sequences of period 2L - 1 in blocks of size v = 4,8, and 16, for L ranging over the odd values from 7 to 127. When L = ±3 mod 8, no irreductible windmill polynomials were found. For the other odd values of L, primitive windmill polynomials seem to occur about twice as frequently as would be expected from probabilistic considerations, so that they are in fact very common. For such values of L, roughly 2/L of all windmill polynomials with given v appear to be primitive.
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| 3559. |
- Smeets, Ben
(författare)
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Linear complexity profile of sequences over the field GF(Q)
- 1988
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Ingår i: ; , s. 217-217
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Konferensbidrag (refereegranskat)abstract
- Summary form only given. The author extends Reuppel's concept of the linear complexity profile of binary sequences to sequences over an arbitrary finite field and provides formulas for the expected linear complexity and its variance of sequences Sn of length n over GF(q). He shows that the variance approaches 1/q when q approaches ∞. He presents criteria that could be useful when using the linear complexity profile for investigating the randomness of sequences over GF(q). Finally, the author investigates how useful these criteria are by comparing the results with other randomness tests.
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| 3560. |
- Smeets, Ben
(författare)
-
On the number of polynomials over GF(2) that factor into 2, 3 or 4 prime polynomials
- 1985
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Ingår i: BIT Numerical Mathematics. - 0006-3835. ; 25, s. 667-674
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Tidskriftsartikel (refereegranskat)abstract
- In this paper a simple method is presented to derive formulas for the number of polynomials over GF(2) which factor into two, three, and four prime polynomials only. A table is given, summarizing the above numbers for polynomials of degree up to 127. Furthermore, the computed values are compared with an asymptotic approximation for these values.
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